During arthroscopic surgery, a small incision is made in the skin covering the arthroscopic site or joint, and a cannula is inserted in the incision to provide a pathway for surgical instruments to be placed in the joint and manipulated through arthroscopic visualization. Surgical instruments inserted through cannulas must be long and thin—this presents limitations on instruments for cutting tissue, as the diameter of the cannula ordinarily limits the width of the cutting implement.
Retrograde drilling of sockets and tunnels for ACL reconstruction using a flip cutter is known and described, for example, in U.S. application Ser. No. 12/114,599, filed on May 2, 2008, published as U.S. Publ. No. 2009/0275950 A1 and EP 1987786, the disclosures of which are incorporated by reference herein. This prior published application describes a flip retrograde cutter having a blade, preferably a flip blade, that is configured to articulate between at least a first “straight” position, for example, substantially parallel to a longitudinal axis of the flip retrograde cutter, and at least a second “flip” position, for example, a non-parallel position relative to the longitudinal axis of the flip retrograde cutter. Using such a flip retrograde cutter, a recipient site socket can be created from the inside out, i.e., using a retrograde technique, with minimal incisions of distal cortices and reduced intraarticular bone fragmentation of tunnel rims.
The flip retrograde cutter described above may be employed in a retrograde manner to form a recipient socket (to accommodate an osteochondral transplant, or to allow retrograde fixation of a graft within two sockets, for example). Formation of the recipient socket begins by inserting the flip retrograde cutter in the “straight” configuration into the joint space, preferably from the outside in, through a small diameter tunnel. A locking tube of the instrument is then retracted so that the blade can be articulated into the “flip” configuration, i.e., into a position other than the “straight” position and preferably at about 90 degrees to the longitudinal axis of the instrument. The device is locked in the “flip” position by tightening the locking tube. A socket is created by conducting a drilling operation, i.e., by rotating the instrument, while the device is pulled outwardly.
A need exists for a mechanism that facilitates flipping of the blade in the above-described instrument by converting linear movement of the shaft into rotational movement of the cutter blade (without the need to manually flip the cutter blade into position within the joint).